Acoustic Emission of Frangible, Composite, Concrete and Metallic Radar Towers

ABSTRACT: A novel hybrid acoustic emission (AE) and guided wave (GW) inspection approach for the inspection of radar towers is presented in this proposal. Many radar sites are over 50 years old and it is important to keep them in good repair, as they are a critical intelligence component that provides advanced aircraft notification. It is proposed to supplement the passive AE inspection method with active GW inspection. AE events can provide a trigger for immediate GW nondestructive testing, allowing inspection redundancy and significantly improved damage classification. Active GW inspection is highly effective at locating and sizing damage (i.e., cracks, corrosion), and is currently used in the pipeline industry to reliably inspect up to 600 feet from a single location. Additionally, the use of GW sensors sensitive to shear horizontal type waves can provide several benefits over traditional AE sensors, including: simpler, more efficient, and more robust source localization, increased sensitivity to certain types of crack growth, and decreased sensitivity to environmental noise. A hybrid AE-GW inspection technology has the potential to revolutionize the traditional AE market. This proposal describes how this technology can be developed and adapted to address the monitoring and inspection needs of existing and future radar towers.; BENEFIT: As a result of the proposed work, a novel hybrid acoustic emission (AE) and guided wave (GW) inspection method will be born. The integration of active GW inspection will increase damage sizing and characterization capability. The use of special shear-type sensors will increase detectability and reliability of AE systems. Increased sensitivity to damage and damage characterization capability will result in a more complete understanding of a structures current damage stage and the rate of damage progression. This will allow for improved scheduling and advanced notice for maintenance operations, reducing the time and cost devoted to maintenance. In some cases, damage not detected using the traditional AE method may be detected using the hybrid AE-GW method. Due to these reasons, the AE-GW method has the potential to revolutionize the traditional AE market. After application of the AE-GW inspection method to radar towers, the sensors, techniques, and analysis algorithms developed herein will be quickly adapted for commercialization and implementation onto many other structures typically inspected using the traditional AE method.